Two Democratic senators introduced the Honest Ads Act on Thursday, which would make online political advertising more transparent and more unavailable to foreign entities

The legislation was introduced in response to recent disclosures by big tech companies that Russia used their platforms to purchase political ads during the election

Companies like Facebook, Twitter, and Google have reserved judgment on the bill, saying that they look forward to discussing it further with lawmakers

New legislation introduced by Democratic Sens. Amy Klobuchar and Mark Warner on Thursday aims to make the process of purchasing political advertisements more transparent — and more difficult for foreign entities.

The bill, which was cosponsored by Republican Sen. John McCain, was introduced in response to Facebook's disclosure last month that Russia-linked accounts bought $100,000 worth of political ads during the 2016 presidential election.

The legislation would require "digital platforms with at least 50,000,000 monthly viewers to maintain a public file" of ads purchased by individuals or groups who spend more than $500 on ads over the course of one year, according to a draft of the bill.

It is illegal for a foreign government or entity to spend money on political ads that express advocacy, or endorse one particular candidate over another, in an attempt to sway a US election. But the current laws governing foreign-bought ads that aim to promote junk news, or one particular issue over another, are murkier.

The Honest Ads Act would amend the Federal Election Campaign Act of 1971, however, by requiring that online platforms make "reasonable efforts" to ensure that political ads are not "directly or indirectly" purchased by foreigners to "influence the American electorate."

The bill's definition of a "qualified political advertisement," moreover, includes anything that "communicates a message relating to any political matter of national importance, including a national legislative issue of public importance."

The legislation would also require platforms like Facebook and Google to allow "online public inspection" of the record of ads purchased by a particular group or individual, as well as "a description of the audience targeted" and the "number of views generated" from the ad.

Warner said in a statement that, "at the end of the day, it is not too much to ask that our most innovative digital companies work with us by exercising additional judgment and providing some transparency."

But Facebook, Twitter, and Google have yet to explicitly endorse the bill in its current form.

"We have already announced the steps Facebook will take on our own and we look forward to continuing the conversation with lawmakers as we work toward a legislative solution," said Facebook's vice president of US public policy, Erin Egan.

"We look forward to engaging with Congress and the FEC on these issues," said a Twitter spokesperson.

"We're evaluating steps we can take on our own platforms and will work closely with lawmakers, the FEC, and the industry to explore the best solutions," Google said.

Klobuchar, meanwhile, was realistic about the companies' responses during a press conference on Thursday.

"I'm not going to tell you they support this bill right now," she said.

Critics have said that while the bill is a positive step forward, it does not address the issue of how easy it was for Russia-linked accounts to spread disinformation and incite unrest.

Six Russia-linked Facebook accounts analyzed by Columbia University researcher Jonathan Albright posted content that was shared over 340 million times between them, he found.

Twitter bots spread junk news to swing states leading up to the election, according to a study conducted by Oxford's Computational Propaganda Project, and actors were hired by Russia to pose as American voters and make anti-Hillary Clinton videos on YouTube. The Russian content appeared on Instagram and even Pokemon Go, CNN reported.

A Russian troll factory known as the Internet Research Agency went as far as to pay US activists to help organize protests across the country, according to an RBC investigation.